Method and apparatus to determine bone mineral density utilizing a flat panel detector

ABSTRACT

A method and apparatus for using a flat panel detector to determine bone mineral density are provided. The apparatus includes a dual energy X-ray emitter, a flat panel detector for receiving X-rays sent from the X-ray emitter, and may optionally include an image corrector, adapted to emit corrected image information. The apparatus also includes a basis material decomposer that includes a calibration database, the decomposer being adapted to create a bone image and a soft tissue image. The apparatus further includes a bone mineral density calculator that is adapted to compute bone mineral density from the first image, and a display for displaying at least the computed bone mineral density. A method for using a flat panel detector to detect multiple disease states is also provided. The method includes emitting X-rays from a dual energy X-ray source through an area of a patient&#39;s body sought to be imaged and receiving X-rays with a flat panel detector. The method also includes generating multiple images, using dual energy X-ray absorptiometry, to detect for a first disease state and a second disease state and analyzing the images for the first and second disease states. The first disease state includes lung cancer, breast cancer, pneumonia, chronic obstructive pulmonary disease, tuberculosis, bone fracture or an abnormally sized or shaped organ and the second disease state comprises osteoporosis.

BACKGROUND OF INVENTION

[0001] Certain embodiments of the present invention relate to thedetection of osteoporosis and more particularly relates to the detectionof bone mineral density using a flat panel detector.

[0002] Osteoporosis is a disease of the skeleton in which the amount ofcalcium present in the bones slowly decreases to the point where thebones become brittle and prone to fracture. In other words, the boneloses density. Osteoporosis is diagnosed when bone density has decreasedto the point where fractures occur even under mild stress, also referredto as the fracture threshold.

[0003] In the United States alone, ten million people have osteoporosisand eighteen million more have low bone mass (80% of whom are women), acondition which indicates an increased risk of developing osteoporosis.Osteoporosis is responsible for one-and-one-half million fracturesannually. As a result, statistics indicate that one of every two womenover age fifty will have an osteoporosis-related fracture in theirlifetime. As a reference, a woman's risk of an osteoporosis-relatedfracture is equal to her combined risk of acquiring breast, uterine andovarian cancer. The most common sites of fractures are the hip, spine,wrist and ribs. Perhaps the most devastating of these fractures is thehip fracture. On average, 24% of hip fractures in patients 50 and overlead to death within one year. Osteoporotic fractures such as these costan estimated $18 billion annually.

[0004] Unfortunately, bone density loss occurs without symptoms. Bonemineral density (BMD) measurements can be used to detect osteoporosisbefore fracture, determine the probability of a future fracture,determine the rate of bone loss, and monitor the efficacy of treatment.Additionally, effective treatments currently exist, thus highlightingthe desirability for early detection of the disease. Nonetheless, due tothe lack of symptoms, osteoporosis is underdiagnosed and frequently goesundetected.

[0005] Due to the frequency of osteoporotic fractures, the NationalOsteoporosis Foundation (NOF) currently recommends broad categories ofwomen to receive bone mineral density testing: all women ages 65 andolder, postmenopausal women having any of the risk factors forosteoporotic fracture (low body weight, history of fracture, Asian orCaucasian, cigarette smoking, estrogen deficiency, early menopause, lowcalcium intake, alcoholism, recurrent falls, and inadequate physicalactivity), and all postmenopausal women who have already had a fracture.Additionally, many women with these same risk factors are recommended tohave mammography tests. It may also be desirable to test women withthese same risk factors for lung cancer, pneumonia, or a bone fracture.

[0006] There are two basic methods to measure the density of bone. Thesemethods involve passing either X-rays or ultrasound waves through thebone being assessed, and measuring the effect that the bone has on theserays or waves. Within the field of X-rays, the measurement may utilizethe principals of either radiogrammetry (i.e., standard X-raytechniques) or absorptiometry. In this context, radiogrammetry (orradiography) involves the use of registration on film of thedifferential absorption of X-ray beams passing through a specimen.Absorptiometry refers to a chemical analysis of gases, liquids or solidsto measure densities, porosities as well as coating, plating andinsulation thickness. In the context of osteoporosis, absorptiometry isuse to measure bone densities. There are two types of absorptiometry,single energy X-ray absorptiometry (“SXA”) and dual energy X-rayabsorptiometry (“DXA”). Single energy X-ray absorptiometry involves theuse of X-rays at a single wavelength to measure bone mineral content (inthe detection of osteoporosis). Dual energy X-ray absorptiometryinvolves the use of X-rays at two wavelengths to measure bone mineralcontent (in the detection of osteoporosis). DXA is used when SXA is notfeasible, i.e., in areas with variable soft tissue and composition suchas the spine or hip.

[0007] Two types of BMD tests used in diagnosing osteoporosis thatutilize X-rays are peripheral BMD on the wrist or heel (radiogrammetryusing a pencil beam or a fan beam), and dual energy X-ray absorptiometryon the hip, spine or femur. For example, osteoporosis tests and lungcancer tests are currently performed in separate units and/or stations(in separate rooms or areas): the osteoporosis test using a pencil beamor fan beam on the heel or wrist, and the lung cancer test using astandard radiography unit. While the scanning time for X-rays isgenerally short (on the order of less than one second), the setup timefor each of these tests can take ten minutes or more.

[0008] Due to the overlap in symptoms, ages and gender in people whohave osteoporosis and/or other disease states (e.g., breast cancer, lungcancer and pneumonia, chronic obstructive pulmonary disease,tuberculosis, bone fracture or an abnormally sized or shaped organ),there is a particular need for a dual-purpose screening method capableof detecting both osteoporosis (or BMD) and at least one other diseasestate.

SUMMARY OF INVENTION

[0009] Certain embodiments relate to an apparatus for using a flat paneldetector to determine bone mineral density. The apparatus includes adual energy X-ray emitter, a flat panel detector for receiving X-rayssent from the X-ray emitter, and may optionally include an imagecorrector adapted to provide corrected image information. The apparatusalso includes a basis material decomposer comprising a calibrationdatabase. The decomposer is adapted to create first and second images,the first image comprising a bone image and the second image comprisinga soft tissue image. The apparatus further includes a bone mineraldensity calculator adapted to compute bone mineral density from thefirst image, and a display for displaying at least the computed bonemineral density.

[0010] Certain embodiments relate to a method for using a flat paneldetector to detect multiple disease states. The method includes emittingX-rays from a dual energy X-ray source through an area of a patient'sbody sought to be imaged and receiving X-rays with a flat paneldetector. The method also includes generating multiple images, usingdual energy X-ray absorptiometry, to detect for a first disease stateand a second disease state and analyzing the images for the first andsecond disease states. The first disease state includes lung cancer,breast cancer, pneumonia, chronic obstructive pulmonary disease,tuberculosis, chronic obstructive pulmonary disease, bone fracture or anabnormally sized or shaped organ and the second disease state comprisesosteoporosis. The analyzing step may optionally include determining theaerial density (g/cm²) or volume density (g/cm³) of a bone sought to beimaged.

BRIEF DESCRIPTION OF DRAWINGS

[0011]FIG. 1 illustrates an apparatus using a flat panel detector todetermine bone mineral density according to one embodiment of thepresent invention.

[0012]FIG. 2 illustrates an apparatus using a flat panel detector todetermine bone mineral density according to another embodiment of thepresent invention.

[0013]FIG. 3 illustrates a method of using a flat panel detector todetect multiple disease states according to one embodiment of thepresent invention.

[0014]FIG. 4 illustrates a method of using a flat panel detector todetect multiple disease states according to another embodiment of thepresent invention.

[0015]FIG. 5 illustrates a method of using a flat panel detector todetect multiple disease states according to yet another embodiment ofthe present invention.

[0016]FIG. 6 illustrates a method of determining bone mineral densityaccording to still another embodiment of the present invention.

[0017]FIG. 7 illustrates a method of using a flat panel detector todetermine bone mineral density according to one embodiment of thepresent invention.

[0018] The foregoing summary, as well as the following detaileddescription of certain embodiments of the present invention, will bebetter understood when read in conjunction with the appended drawings.It should be understood, however, that the present invention is notlimited to the arrangements and instrumentality shown in the attacheddrawings.

DETAILED DESCRIPTION

[0019] Turning to FIGS. 1 and 2, an apparatus 100 utilizing a flat paneldetector (FPD) 102 to measure bone mineral density and detectosteoporosis is shown. In order to use the FPD 102 in this manner, dualenergy X-rays 104 (i.e., both a high energy X-ray and a low energy X-rayfollowing one another in time) are emitted in succession from an X-raysource 106 and passed through the portion of the body sought to beimaged. High energy X-rays 104 and low energy X-rays 104 are received bythe FPD 102 at separate times and two images are created, a high-energyimage and a low-energy image, respectively. The images may be displayedor may simply be stored as data. The image corrector 108 corrects theimages for artifacts, scatter, etc. (using, for example, calibrationvalues) to compensate for imperfections in the X-ray source 106 or FPD102.

[0020] In further detail, the dual energy flat panel detector (FPD) 102takes two successive X-ray images of the chest at different energylevels. The dual energy X-rays include a high energy (e.g., 110-150 kVp)and a low energy (e.g., 60-80 kVp) X-ray. The successive X-ray imagesare generally taken less than one second apart, for example, about 200milliseconds apart.

[0021] Once the images are corrected, a basis material decomposition isperformed using the basis material decomposer 110. The basis materialdecomposer 110 estimates and separates the X-ray absorption caused bythe soft tissue and the X-ray absorption caused by the bone (i.e., thehard tissue). The basis material decomposition is performed using thethicknesses of the bone and soft tissue (which are relatively easy tocompute), and a table including calibration values for X-raydecomposition in various thicknesses of materials that are similar incontent to bone and soft tissue.

[0022] Aluminum and lucite, respectively, are generally similar enoughin content to use to predict how the X-ray 104 should be absorbed by thebone and soft tissue. Through the use of the calibration table with thebasis material decomposer 110, the amount of absorption caused by thebone and soft tissue, respectively, is estimated. From the separation ofthe bone and soft tissue data, bone and soft tissue images aregenerated. The images may be displayed on a monitor for viewing.

[0023] Referring to FIGS. 1, 2, 6 and 7, the bone image is used todetect BMD or osteoporosis as follows. Beginning with the method of FIG.6, a basis mineral decomposition is performed at step 602 using a basismaterial decomposer 110. The basis material decomposer 110 may include adatabase 112 of estimates of X-ray absorption from materialsapproximating bone and soft tissue, for various thicknesses, includingthe estimated thickness of bone and/or soft tissue depicted in theimage. As described above, two materials which may be useful forestimating the X-ray absorption are lucite and aluminum, for soft tissueand bone, respectively. Second, a bone mineral density is calculated atstep 604, for example using a bone mineral density calculator 114. Thecalculated bone mineral density is then compared at step 606 to at leastone predetermined bone mineral density using the comparing circuit 116.The BMD comparison at step 606 may compare the patient's BMD to theaverage, mean, etc. of BMD in people who should have similar bonemineral densities (e.g., people of the same race, gender, age, etc.).The BMD comparison at step 606 may additionally or alternatively beperformed for previous BMD calculations for the same patient (e.g., tosee how the disease is progressing, whether it has been arrested, and/orwhether medication is proving successful). To accomplish the comparisonat step 606, the bone mineral density calculator 114 and/or comparingcircuit 116 may include a database 118 of bone mineral densities for thesame patient or a table of bone mineral densities for other people. Oncethe comparison at step 606 is complete, the calculated bone mineraldensity, other predetermined bone mineral densities and/or the imagesmay be presented on a display 120 for a physician's review 710.

[0024] Focusing in particular on the bone image, the bone mineraldensity calculator 114 calculates BMD “score,” e.g., a relativeintensity is determined from comparing the intensity of the X-raysabsorbed passing through the bone to a baseline (i.e., where the X-rays104 did not pass through bone). The relative intensity may be determinedby comparing the bone intensity to the non-bone intensity in either thebone image or the soft tissue image (or a combination of both). Therelative density is referred to as the aerial density of the bone and/orthe BMD score. Once the BMD score is calculated at step 604, it iscompared to either a population table or prior data for the patientusing the comparing circuit 116. The population table is a table of bonedensity score information that may be based on many factors: age,gender, ethnicity, medications a patient is taking, etc. Prior data forthe particular patient may include, for example, prior BMD scores orearlier radiographic images of the patient. In comparing at step 606 theBMD score to prior data for the patient, it may be determined whether apatient's osteoporosis is progressing or whether a patient's medicationsare treating the disease effectively. Thus, the physician reviewing thebone image and associated BMD information is able to analyze whether apatient has osteoporosis or whether the patient's medication iseffectively treating the disease.

[0025] Referring generally to FIG. 1, the X-ray source 106, FPD 102,image corrector 108, 208, basis material decomposer 110, BMD calculatorand display 120 may be implemented using combinatorial logic, an ASIC,through software implemented by a CPU, a DSP chip, or the like.Additionally, the foregoing hardware elements may be part of hardwarethat is used to perform other operational functions. The databases 112,118, comparing circuit 116, intensities BMD scores and tables may bestored in registers, RAM, ROM, or the like, and may be generated throughsoftware, through a data structure located in a memory device such asRAM or ROM, and so forth.

[0026] The apparatus 100 may also be included in one of the following: aradiography unit (or RAD unit), a mammography unit, a cardiography unit,or a vascular imaging system. In this way, the apparatus 100 can beutilized in a way that enables a patient to be diagnosed forosteoporosis as well as another disease state without having to sitthrough two full exams.

[0027] According to the method illustrated in part in FIGS. 3-7, anX-ray source 106 emits at step 302 a high energy X-ray and a low energyX-ray through a portion of the body sought to be imaged. After passingthrough the portion of the body sought to be imaged, the FPD receives atstep 304 the high and low energy X-rays (e.g., the unabsorbed portionsthereof).

[0028] Once received, the unabsorbed high and low energy X-rays are usedin conjunction with dual energy imaging software or a dual energyimaging algorithm to generate multiple images at step 306. In oneembodiment, when used to image the chest, the dual energy X-ray 104 isused to generate a standard posterior-anterior (PA) X-ray image, a PAimage of the chest with the bones removed (“soft tissue image”), and animage of the skeletal system of the chest (“bone image”).

[0029] Once these images are created, the physician analyzes at steps308, 310 the images to detect multiple disease states. For example, thesoft tissue image may be used to detect lung cancer or pneumonia and thebone image may be used to detect BMD or osteoporosis. The analysis ofthe bone image may include determining the aerial density (g/cm²) orvolume density (g/cm³) of the bone of interest. This analysis mayinvolve, for example, the use of image processing and segmentationalgorithms.

[0030] As a result, with the use of the FPD 102 alone and only one exam,a physician can check a patient, for example, for both lung cancer andosteoporosis. A physician can also check for breast cancer andosteoporosis, which is desirable because their risk factors overlapsignificantly.

[0031] Referring FIGS. 3, 6 and 7, a physician may analyze 308 thestandard radiograph or a soft tissue image for at least the following:lung cancer, breast cancer, pneumonia, chronic obstructive pulmonarydisease, tuberculosis, bone fracture or an abnormally sized or shapedorgan. Utilizing the skeletal system image and the data displayed as aresult of the basis material decomposition at step 602, BMD calculationat step 604 and BMD comparison at step 606, the physician may analyze atstep 310 the image (and/or the displayed data associated with the image)for the detection of osteoporosis.

[0032] As illustrated in FIG. 3, the analysis for the first and seconddisease states at steps 308, 310 may be performed in series by onephysician. As illustrated in FIG. 4, however, the analysis may beperformed in parallel by multiple physicians or at separate times atsteps 402, 404. For example, a physician administering the flat panelscan is knowledgeable in reading mammograms, but may not skilled indiagnosing osteoporosis or understanding the bone mineral densityinformation. He or she may have the image reviewed later by a colleagueat the same location who is skilled in diagnosing osteoporosis, or evensend a bone image to an osteoporosis specialist in another location(either by teleradiography or otherwise). As illustrated in FIG. 5, nimages may be generated by the FPD and analyzed for n disease states atsteps 502, 504. For example, one physician who is competent to read astandard radiograph for a broken bone, may desire others to diagnose thepatient for breast cancer and osteoporosis. He or she can send the softtissue image to a breast cancer specialist and a bone image to anosteoporosis expert (either by teleradiography or otherwise). Thus,three separate physicians can review the images to diagnose threedifferent disease states (in this case, bone fracture, breast cancer andosteoporosis).

[0033] Of course, the availability of multiple images may be useful indiagnosing each individual disease state. For example, in lung cancerscreening, a soft tissue image may show nodules and a bone image mayshow whether or not such nodules are calcified. Both would be useful indiagnosing bone cancer. The method illustrated in FIG. 3 demonstratesthat the parallel analysis permitted in FIGS. 4 and 5 is not required.

[0034] In short through the use of only one dual energy x-ray, thephysicians may determine bone mineral density, analyze for osteoporosisand/or analyze for multiple disease states, osteoporosis and one or moreof several others. With the ability to perform tests for multipledisease states with only one dual energy X-ray 104 (or multiple dualenergy X-rays using the same unit), the time required to test formultiple disease states may be significantly decreased. The X-ray orradiation exposure to test for multiple disease states may also bereduced.

[0035] Detection for multiple disease states may help prolong lives andis economically sensible. Due to the increased health care needs andincreased likelihood of death associated with bone fractures among theelderly, early detection of osteoporosis is desirable. Becauseosteoporosis is treatable, early detection may extend the healthy livesof those with the disease.

[0036] While particular embodiments of the invention have been shown, itwill be understood, of course, that the invention is not limited theretosince modifications may be made by those skilled in the art,particularly in light of the foregoing teachings. It is, therefore,contemplated that the appended claims will cover any such modificationsas incorporate those features that constitute the essential features ofthese improvements within the true spirit and the scope of theinvention.

1. A method for using a flat panel detector to analyze multiple diseasestates, comprising: emitting X-rays from a dual energy X-ray sourcethrough at least one area of a patient's body sought to be imaged;receiving said X-rays passed through the patient's body by a flat paneldetector; generating at least first and second images, using dual energyX-ray absorptiometry, based on signals read-out of the flat paneldetector, to diagnose first and second disease states, wherein saidfirst disease state constitutes one of lung cancer, breast cancer,pneumonia, chronic obstructive pulmonary disease, tuberculosis, bonefracture or an abnormally sized or shaped organ and said second diseasestate constitutes osteopenia; and displaying at least the first image todiagnose the first disease state and the calculated bone mineral densityto diagnose the second disease state.
 2. The method of claim 1 whereindiagnosing said second disease state comprises conducting a basismaterial decomposition on said second image using a basis materialdecomposer.
 3. The method of claim 2 wherein diagnosing said seconddisease state further comprises calculating a bone mineral density basedon signals read-out of the basis material decomposer.
 4. The method ofclaim 3 wherein diagnosing said second disease state further comprisescomparing said bone mineral density to at least one predetermined bonemineral density.
 5. The method of claim 1 wherein said displaying stepfurther comprises displaying at least one of said predetermined bonemineral densities.
 6. The method of claim 1 further comprising analyzingsaid first image for the first disease state and analyzing said secondimage for the second disease state.
 7. The method of claim 1 whereinsaid emitting step comprises emitting the X-rays through a human torso.8. The method of claim 7 wherein said emitting step comprises emittingthe X-rays through a lung.
 9. The method of claim 7 wherein saidemitting step comprises emitting the X-rays through breast tissue. 10.The method of claim 1 wherein said emitting step comprises emittingX-rays through a hip bone, for purposes of diagnosing fracture detectionor osteopenia.
 11. The method of claim 1 wherein said emitting stepcomprises emitting X-rays through at least one extremity, for purposesof diagnosing fracture detection or osteopenia.
 12. The method of claim6 wherein said analyzing step includes determining the aerial density(g/cm²) of a bone sought to be imaged.
 13. The method of claim 6 whereinsaid analyzing step includes determining the volume density (g/cm³) of abone sought to be imaged.
 14. A method for using a flat panel detectorto measure bone mineral density, comprising: emitting X-rays from a dualenergy X-ray source through at least one area of a patient's body soughtto be imaged; receiving said X-rays passed through the patient's body bya flat panel detector; generating a first image, using dual energy X-rayabsorptiometry, based on signals read-out of the flat panel detector, todiagnose a first disease state, wherein said first disease stateconstitutes one of lung cancer, breast cancer, pneumonia, chronicobstructive pulmonary disease, tuberculosis, bone fracture or anabnormally sized or shaped organ; generating a second image, using dualenergy X-ray absorptiometry, based on signals read-out of the flat paneldetector, to diagnose a second disease state, wherein said seconddisease state constitutes osteopenia; and displaying at least the firstimage to analyze the first disease state; and displaying informationderived from said second image to analyze the second disease state. 15.The method of claim 14 wherein diagnosing said second disease statecomprises conducting a basis material decomposition on said second imageusing a basis material decomposer.
 16. The method of claim 15 whereindiagnosing said second disease state further comprises calculating abone mineral density based on signals read-out of the basis materialdecomposer.
 17. The method of claim 16 wherein diagnosing said seconddisease state further comprises comparing said bone mineral density toat least one predetermined bone mineral density.
 18. The method of claim14 wherein said first disease state is analyzed by a first physician andsaid second disease state is analyzed by a second physician.
 19. Themethod of claim 14 wherein said first and second disease states areanalyzed by a first physician.
 20. The method of claim 14 wherein saidemitting step comprises: emitting X-rays from a dual energy X-ray sourcethrough at least one area of a patient's body sought to be imaged whileconducting a chest X-ray examination; and emitting X-rays from a dualenergy X-ray source through at least one area of a patient's body soughtto be imaged while conducting a bone density test.
 21. The method ofclaim 14 wherein said emitting step comprises emitting a low energyX-ray and a high energy X-ray from a dual energy X-ray source.
 22. Amethod for using a flat panel detector to diagnose two or more diseasestates, comprising: emitting X-rays from a dual energy X-ray sourcethrough first and second portions of a patient's body sought to beimaged; receiving X-rays through the use of a flat panel detector;generating at least first and second images, using dual energy X-rayabsorptiometry, based on signals read-out of the flat panel detector, todiagnose first and second disease states, wherein said first diseasestate constitutes one of lung cancer, breast cancer, pneumonia, chronicobstructive pulmonary disease, tuberculosis, bone fracture or anabnormally sized or shaped organ and said second disease stateconstitutes osteopenia; and analyzing at least the first image for thefirst disease state and at least the second image for bone mineraldensity.
 23. The method of claim 22 wherein analyzing said second imagecomprises: conducting a basis material decomposition on said secondimage using a basis material decomposer; calculating a bone mineraldensity based on signals read-out of the basis material decomposer; andcomparing said bone mineral density to at least one predetermined bonemineral density.
 24. The method of claim 22 wherein said emitting stepcomprises: emitting X-rays from a dual energy X-ray source through saidfirst body portion while conducting an X-ray examination; and emittingX-rays from a dual energy X-ray source through said second body portionwhile conducting a bone density test.
 25. The method of claim 22 whereinsaid emitting step comprises emitting a low energy X-ray and a highenergy X-ray from a dual energy X-ray source.
 26. A method for screeningmultiple disease states using a flat panel detector comprising: emittingX-rays from a dual energy X-ray source through at least one area of apatient's body sought to be imaged while conducting a chest X-rayexamination; emitting X-rays from a dual energy X-ray source through atleast one area of a patient's body sought to be imaged while conductinga bone density test; receiving said X-rays passed through the patient'sbody by a flat panel detector; generating at least first and secondimages, using dual energy X-ray absorptiometry, based on signalsread-out of the flat panel detector, to diagnose first and seconddisease states, wherein said first disease state constitutes one of lungcancer, breast cancer, pneumonia, chronic obstructive pulmonary disease,tuberculosis, bone fracture or an abnormally sized or shaped organ andsaid second disease state constitutes osteopenia; and displaying the atleast two images to diagnose the first disease state and the seconddisease state.
 27. The method of claim 26 wherein diagnosing said seconddisease state comprises conducting a basis material decomposition onsaid second image using a basis material decomposer.
 28. The method ofclaim 27 wherein diagnosing said second disease state further comprisescalculating a bone mineral density based on signals read-out of thebasis material decomposer.
 29. The method of claim 28 wherein diagnosingsaid second disease state further comprises comparing said bone mineraldensity to at least one predetermined bone mineral density.
 30. Anapparatus utilizing a flat panel detector to determine bone mineraldensity comprising: a dual energy X-ray emitter; a flat panel detectorfor receiving X-rays sent from said X-ray emitter; an image corrector,in communication with said flat panel detector, adapted to emitcorrected image information; a basis material decomposer, incommunication with said image corrector, comprising a calibrationdatabase, said decomposer being adapted to create first and secondimages, said first image comprising a bone image and said second imagecomprising a soft tissue image; a bone mineral density calculator, incommunication with said basis material decomposer, said bone mineraldensity calculator being adapted to compute bone mineral density fromsaid first image; and a display, in communication with said bone mineraldensity calculator, for displaying at least the computed bone mineraldensity.
 31. The apparatus of claim 30 wherein said calibration databasecomprises estimates of X-ray absorption from materials approximatingbone and soft tissue.
 32. The apparatus of claim 31 wherein saidmaterials comprise lucite and aluminum.
 33. The apparatus of claim 30wherein said bone mineral density calculator is adapted to compute abone mineral density by comparing intensities in said first image. 34.The apparatus of claim 33 wherein said bone mineral density calculatoris adapted to compute a bone mineral density by comparing intensities insaid first image between a bone area and a non-bone area.
 35. Theapparatus of claim 30 wherein said bone mineral density calculator isadapted to compute an aerial density.
 36. The apparatus of claim 30wherein said bone mineral density calculator is adapted to compute avolume density.
 37. The apparatus of claim 30 wherein said display isadapted to display the bone mineral density computed by said bonemineral density calculator and at least one other bone mineral density.38. The apparatus of claim 37 wherein said at least one other bonemineral density comprises a bone mineral density for the same patient.39. The apparatus of claim 37 wherein said at least one other bonemineral density comprises bone mineral densities of persons other thanthe patient.
 40. The apparatus of claim 30 wherein said bone mineraldensity calculator comprises a comparing circuit.
 41. The apparatus ofclaim 30 wherein said bone mineral density calculator comprises acomparing circuit.
 42. The apparatus of claim 30 further comprising acomparing circuit for a bone mineral density calculator, incommunication with said bone mineral density calculator, said comparingcircuit being adapted to compare the calculated bone mineral densitywith at least one predetermined bone mineral density.
 43. The apparatusof claim 42 wherein said at least one predetermined bone mineral densitycomprises a bone mineral density for the same patient.
 44. The apparatusof claim 42 wherein said at least one predetermined bone mineral densitycomprises bone mineral densities of persons other than the patient. 45.A method for using a flat panel detector to determine bone mineraldensity, comprising: emitting X-rays from a dual energy X-ray sourcethrough at least one area of a patient's body sought to be imaged;receiving said X-rays passed through the patient's body by a flat paneldetector; generating at least first and second images, using dual energyX-ray absorptiometry, based on signals read-out of the flat paneldetector, said first image comprising a bone image and said second imagecomprising a soft tissue image; performing an analysis of at least saidfirst image to calculate a bone mineral density; and displaying at leastthe calculated bone mineral density.
 46. The method of claim 45 whereinsaid displaying step further comprises displaying at least onepredetermined bone mineral density.
 47. The method of claim 45 whereinsaid performing step comprises: conducting a basis materialdecomposition on said first image using a basis material decomposer;comparing an intensity in a bone area of said first image with anintensity of a non-bone area using a comparing circuit; and calculatinga bone mineral density based on signals read-out of the comparingcircuit.
 48. The method of claim 45 wherein said intensity of a non-bonearea is based on said first image.
 49. The method of claim 45 whereinsaid intensity of a non-bone area is based on said second image.
 50. Themethod of claim 45 wherein said intensity of a non-bone area is based onsaid first image and said second image.